Determining tennis' greatest player

Peter Keating is a senior writer at ESPN The Magazine, where he covers investigative and statistical subjects. He started writing "The Biz," a column looking at sports business from the fan's point of view, in 1999. He also coordinates the Magazine's annual "Ultimate Standings" project, which ranks all pro franchises according to how much they give back to fans. His work on concussions in football has earned awards from the Deadline Club, the New York Press Club and the Center for the Study of Sport in Society.

IF YOU WANT TO KNOW THE BEST ATHLETE or team in any sport, there's a straightforward way to figure it out: Have everyone play everyone else a significant number of times and see who earns the best record. Of course, in most sports, that's impossible to do, which often leads to the mother of all sports riddles: If Team A beats Team B, and Team B beats Team C, and Team C beats Team A, how do you rank the three teams?

Well, thanks to scientists in a field called complex network analysis, there's a novel way to solve this conundrum -- and settle a whole lot of bar arguments.

A network is simply any system of points connected by paths that carry information. Networks are everywhere. Groups of proteins that interact within cells are networks. A large set of tennis pros who routinely play each other is a network. So is your set of Facebook friends. So is the Internet itself, for that matter.